Easy Motion System Integration: Practical Strategies, Tools

Inside Machines: When designing machine motion controls, remember that motion starts at the load. Applications that guide motion system integration decisions can result in a more strategic machine design for more efficient and intuitive operation.

03/07/2012


Many engineers begin with a machine motion concept in the control environment, but it’s important to keep in mind that motion starts at the load. Rather than a machine builder or plant engineer following a standard blueprint for product design, the product application should ideally inform motion system integration decisions. A strategic design approach yields machines that operate more efficiently and are more intuitive to use.

State-of-the-art motion control technologies enable integration of robotics into any application that can be defined in degrees of mechanical freedom. Three-dimensional movement can be coded into one block, integrating programming for recovery, honing, an

Motion system challenges

Traditional approaches to motion control engineering have generally been based on a fairly simple model of a motion controller, servo, and motor control. With the industry trending toward highly synchronized ac servos and robotics, more customized motion control applications are being successfully deployed in logistics, material handling, plastic machines, metalwork, and other industries in which motion can, in some cases, be challenging to incorporate.

A standard linear motion application—which might be found in machining, extruders, and clamp and positioning applications—tends to serve a sole purpose, with consistency trumping the need for speed or flexibility. Conversely, a state-of-the-art application, such as pharmaceutical blister packaging, may include variable package sizes and doses, smaller runs, equipment washing, and the ability to switch from capsules to tablets or liquid products. Design issues would include not only high reliability, but precision speed, flexibility, and ease of programming to accommodate shifting product variables.

Machine design has always entailed some level of complexity. In the past, a typical system comprised a single machine solving a simple problem, such as a mechanical carton packaging machine powered by a single motor, with a 1:1 revolution-product ratio. Switching to a different product or changes in package sizing often means production downtime to wield wrenches and change-out parts, with some tasks requiring several hours of skilled labor. Although lacking in speed and flexibility, with the proper settings an unsophisticated mechanical process can offer viable and consistent performance.

Although mechanics have not changed substantially, application demands have multiplied. In terms of the hierarchy of complexity, the dynamic packaging industry, in particularly consumer goods packaging, aptly exemplifies the next challenges in motion control integration. A cartoning operation today might comprise 20 ac servo motors. Packaging cycle rates range much higher in consumer goods products. For example, a confectionary wrapping machine may require 3,000 wraps per minute, comprising multiple steps—wrapper from spool, cutting, product retrieval and positioning, wrapper twisting, and turning. The complexity problem relates not only to scale, but programming. Consumer packaging machinery often handles a variety of product. The machine environment must accommodate turbo speeds and the flexibility to convert new SKUs introduced to the market.

Common language, standard code

In the past it was not unusual for the proprietary programming of a complex operation from scratch to be years in development. Today’s complex machine designs do not necessitate complex programming. The key is to identify ways in which software can simplify operation and maintenance. Simplicity and code modularity were major achievements in the development of the OMAC PackML (Organization for Machine Automation and Control—Packaging Machine Language) group and ISA88 (International Society of Automation). In particular, ISA88 provides standards pertaining to equipment modules and control modules. ISA88 Part Five ensures that leading vendors provide customers with modular standards, basically an interchangeable block of code for a specified servo motor.

These international codes provide a framework for decreasing complexity by allowing for the programming of one function block, which can be applied 19 times in the example above, rather than programming each motor individually. By building based on ISA88 and PLC Open Motion standards, which provide a suite or range of motions available in a specific motor, the machine engineer can achieve interoperability that was unavailable a decade ago. The resulting definitions of common technical approaches and a unified packaging machine language across plant floors have been important drivers behind recent motion control innovations that enable improved equipment integration and operational consistency in discrete machine process applications.

By standardizing the coding process, code modularity helps facilitate communication from the motion controller to the PLC and HMI. The seamless flow of information is at the core of validation and also enables the simplification of previously complex machines and processes, such as robots and belting systems. The latest controls on the market are smart enough to factor in the dimensions of a primary and secondary product, for example, and auto adjust the machine without the use of complex timers, counters, and other variables. 

Modular multi-axis robotics

Robotic technologies are no longer confined to highly specialized applications. The latest motion control technologies enable the integration of robotics into any application that can be defined in degrees of mechanical freedom.

For example, a continuous case packer in the past comprised a mechanical load ram pushing product into waiting cases, requiring a continuous supply of product and cartons, and an intermittent stop-and-start motion. Creating a design that occupies three dimensions requires taking the ISA88 standard and using a robotic block to combine all three axes together. The three-dimensional movement can be coded into one block, integrating programming for all recovery, honing, and operation movements, and replicated for parallel operations. By incorporating a continuous case packer with three degrees of movement—forward-back, left-right, up-down—to more accurately track conveyor movement, product can be continuously packed without unnecessary energy expenditure and the mechanical wear and tear of continuous stops and starts.

Complex packaging and material handling demand precision accuracy to track conveyor movement and continuously process product without unnecessary energy expenditure and excess mechanical wear and tear. Courtesy: Lenze Americas

So, a case packer that once may have comprised 12 distinct axes can now be programmed using robotic software modules, with auxiliary axes for input and output belts, thereby addressing both speed and recovery. Programming follows a standard “recipe” that can be easily adjusted to any application or product variety that fits within the predefined design space. The approach offers not only speed, performance, and programming ease, but improved reliability and longer machine life.

Centralized control, logic, motion

Motion control automation often comprises multiple machines requiring a powerful and uniform central automation control system. Machine builders are tasked with identifying simple, maintenance-free technologies that can deliver on high-performance dynamic power requirements.

Easy engineering, power, and performance need not be mutually exclusive.

Designed for applications in the packaging and process automation industries, a compact, energy-efficient controller blends a programmable logic controller (PLC), motion controller, and visualization in one compact device to simplify engineering and extend cost savings. Delivering precision motion control in high dynamic multi-axis applications, the device is suitable for gantry systems, robots, conveyers, feeders, and a range of other machines in a line process.

The architecture fits in a tight control cabinet and operates without a fan or battery via an integrated universal power supply (UPS). The controller directs the drive and motor through a programmed sequence of moves, plans each trajectory point, and directs the drive to close the position and velocity loops with the motor. With an integrated Ethernet switch and EtherCAT on-board, the combined controller communicates seamlessly with multiple axes from 2 (1 ms cycle time) up to 64 (6 ms cycle time).

Integration of the EtherCAT-based controller platform combines logic and motion. Featuring automated standard setup via a USB flash drive, the unit minimizes time for commissioning and enables simple device replacement via its pluggable memory card and diagnostics via an integrated Web server. In addition to EtherCAT, the controller complies with IEC 61131-3, PLCopen, and CoDeSys3 industrial standards.

Controller-based system

With the controller, the servo inverter constitutes the controller-based automation system for machines with central motion control. Designed to minimize motion control complexity, the combined unit simplifies machine design, build, and commissioning. This drive system is notably compact and flexible, featuring an easy assembly concept. Extremely short cycle times, 32-bit signal resolution, and an overload capacity of more than 200% make the unit ideal for simple positioning tasks, in addition to highly dynamic, precise, multi-axis applications in handling and packaging machines or robot applications.

The servo inverter single-axis and double-axis modules offer a power range from 0.37 to 15 kW, along with appropriate power supply modules. Plug connectors enable easy wiring. Under normal operating conditions the power supply modules do not require filtering or dc fusing, and have a built-in dynamic brake chopper. Intermediate electrical connections between the drives are cable-free, using an innovative rail system, and are easily installed by setting connector arms. The drive features a variety of cooling technologies, including cold plate, push-through technology, and panel-mounted units.

A seamless flow of information is at the core of designing a powerful and uniform central automation control system. Courtesy: Lenze Americas

Supporting the full spectrum of motor technologies, from standard three-phase motors to synchronous servomotors, the dynamic motor control uses one interface for simple engineering. Intuitive software tools and a central engineering interface make it simple to integrate the unit into automation architectures through EtherCAT. Automatic download of parameters and firmware, along with auto-tuning functions, ensure fast commissioning. It also features integrated safety functionality to simplify the machine design. "Safe Torque Off” (STO) is provided as a standard feature. To implement extended safety networks, variants can achieve the highest safety level (SIL 3, PL e) over EtherCAT (FSoE).

Also see the "Online extra" with technology details below.

- Tom Jensen is program manager, OEM business development, Lenze Americas. Edited by Mark T. Hoske, content manager, Control Engineering, CFE Media, www.controleng.com.

www.lenze.us 

ONLINE extra

Technology details: PLC, motion, visualization

Designed for applications in the packaging and process automation industries, the compact, energy-efficient Lenze 3200 C L-Force Controller blends the programmable logic controller (PLC), motion controller, and visualization in one compact device to simplify engineering and extend cost savings. Delivering precision motion control in high dynamic multi-axis applications, the 3200 C is suitable for gantry systems, robots, conveyers, feeders, and a range of other machines in a line process.

The compact yet powerful 3200 C architecture fits in a tight control cabinet and operates without a fan or battery via an integrated universal power supply (UPS). The controller directs the ECS drive and MCS motor through a programmed sequence of moves, plans each trajectory point, and directs the drive to close the position and velocity loops with the motor.

With an integrated Ethernet switch and EtherCAT on-board, the 3200 C communicates seamlessly with multiple axes from 2 (1 ms cycle time) up to 64 (6 ms cycle time).

Integration of the EtherCAT-based 3200 C Controller platform combines logic and motion, has automated standard setup via a USB flash drive, minimizes time for commissioning, and enables simple device replacement via its pluggable memory card and diagnostics via an integrated Web server. In addition to EtherCAT, the future-proof 3200 C Controller complies with IEC 61131-3, PLCopen, and PLC Designer (CoDeSys3) industrial standards.

Controller-based automation system for machines with central motion control

The controller 3200 C and the i700 servo inverter constitute a state-of-the-art Lenze controller-based automation system for machines with central motion control. Designed to minimize motion control complexity, the i700 simplifies machine design, build, and commissioning. Extremely short cycle times, 32-bit signal resolution, and an overload capacity of more than 200% make the new i700 ideal for simple positioning tasks, in addition to highly dynamic, precise, multi-axis applications in handling and packaging machines or robot applications.

The Servo Inverter i700 single-axis and double-axis modules offer a power range from 0.37 to 15 kW, along with appropriate power supply modules. Intermediate electrical connections between the i700 drives are cable-free, using an innovative rail system, and are easily installed by setting connector arms. The i700 features a variety of cooling technologies, including cold plate, push-through technology, and panel-mounted units.

Supporting the full spectrum of motor technologies, from standard three-phase motors to synchronous servomotors, the dynamic motor control i700 uses one interface for simple engineering. Intuitive software tools and a central engineering interface make it simple to integrate the i700 into automation architectures through EtherCAT. The i700 features integrated safety functionality to simplify the machine design.



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